Conventionally, there have been proposed heat exchangers (hereinafter, also referred to as fin-and-tube heat exchangers) including a plurality of plate-like fins that are stacked with a predetermined fin pitch, and a plurality of heat exchanger tubes that are disposed with a predetermined spacing from one another along the longitudinal direction of the plate-like fins and extend through the plate-like fins along the stacking direction. Further, some of the conventional fin-and-tube heat exchangers proposed use, as a heat exchanger tube, a heat exchanger tube whose cross-section is flat-shaped (hereinafter, also referred to as flat heat exchanger tube).
As an example of conventional fin-and-tube heat exchangers using such a flat heat exchanger tube, in order to minimize performance degradation of the heat exchanger caused by deformation of the plate-like fins or unevenness or any inappropriateness in the fin pitch between the plate-like fins, which occurs during assembling of the heat exchanger, the following heat exchanger has been proposed: “A heat exchanger is formed by integrally brazing the following components: a plurality of plate-like fins 1 that are arranged with a spacing as appropriate; a plurality of tapered flat heat exchanger tubes 3 that are parallel to each other and extend through tapered insertion grooves 2 provided in each of the plate-like fins 1; and a pair of headers 4 and 5 formed by pipes that are disposed with a spacing from each other and communicate with the flat heat exchanger tubes 3. As illustrated in FIG. 3, the insertion grooves 2 provided in each of the plate-like fins 1 are open on one side of each of the plate-like fins 1, and are formed in such a shape that gradually narrows toward the inner side from this one side. That is, the insertion grooves 2 are formed in a tapered shape whose opening-side end portion has a widened portion 2a and whose other end portion has a narrowed portion 2b. The cross-section of the flat heat exchanger tubes 3 has a tapered shape that allows intimate contact of the flat heat exchanger tubes 3 with the narrowed portion 2b side of the insertion grooves 2″ (see Patent Literature 1).
The heat exchanger described in Patent Literature 1 is manufactured by the following method: “To assemble the heat exchanger, first, a predetermined number of plate-like fins 1, for example, 500 plate-like fins 1 are set at predetermined intervals between a pair of jigs (not illustrated), in a state in which erected pieces 10 of adjacent plate-like fins 1 are brought into abutment with each other. The jig is also provided with tapered insertion grooves similar to the tapered insertion grooves 2 provided in each of the plate-like fins 1. Next, as illustrated in FIG. 6(a), a narrowed portion 3b of each of the flat heat exchanger tubes 3 is inserted into the widened portion 2a side of the corresponding insertion groove 2. After the narrowed portion 3b of each of the flat heat exchanger tubes 3 is inserted into the widened portion 2a of the corresponding insertion groove 2, by moving the plate-like fins 1 and the flat heat exchanger tubes 3 relatively, that is, in the direction of the long axis of each of the insertion grooves 2 and the flat heat exchanger tubes 3, the narrowed portion 3b of each of the flat heat exchanger tubes 3 is moved to the narrowed portion 2b side of the corresponding insertion groove 2, thereby bringing each of the flat heat exchanger tubes 3 into intimate contact with the narrowed portion 2b side of the corresponding insertion groove 2 (see FIG. 6(b)). In this case, the widened portion 2a of each of the insertion grooves 2 and the widened portion 3a of the corresponding flat heat exchanger tube 3 are also brought into intimate contact with each other”.